This specification relates to information presentation.
The Internet provides access to a wide variety of resources. For example, video and/or audio files, as well as web pages for particular subjects or particular news articles, are accessible over the Internet. Access to these resources presents opportunities for other content (e.g., advertisements) to be provided with the resources. For example, a web page can include slots in which content can be presented. These slots can be defined in the web page or defined for presentation with a web page, for example, along with search results.
Content item slots can be allocated to content sponsors through a reservation system. For example, publishers can contract with content publishers to publish content items in content slots that are associated with one or more publisher properties. When a content request identifying a particular content slot is received, a content management system associated with the publisher can serve the content items in accordance with any number of rules so as to ensure that the contract terms of the various contracts are satisfied.